Hydraulic subsurface pump and motor



June 3, 1958 e. E. MoHxxlKERNV 2,837,029

HYDRAULIC sUBsURFAcr-J PUMP AND MOTOR Filed Sept. 14. 1954 2 Sheets-Shea?l 1 June 3, 1.958

G. E. MOHNKERN l HYDRAULIC SUBSURFACE;'PUMPl AND MOTOR Filed sept. 14. 1954 2 Sheets-Sheet 2 11/ /N /L/m mi HYDRAULIC SUBSURFACE PUMP AND MGTR Gerald E. Mohnkern, Oil City, Pa., assignor to United States Steel Corporation, a corporation et New ersey Application September 14, 1954, Serial No. 455,930

2 Claims. (Cl. 10S-4o) This invention relates to an improved hydraulically operated subsurface motor and pump combination.

In the subsurface pumping art, such combinations are known as rodless pumps, and they can be used for pumping oil wells in lieu of the more common sucker rod pumps. A rodless pump is installed near the bottom of a well and its motor is actuated by a stream of oil or other liquid pumped down the well. r[he motor conventionally includes a barrel, a piston reciprocable therein and joined to the reciprocable element of the pump, a

main valve for alternately applying power uid to opposite ends of the piston for producing upstrokes and downstrokes, and usually a pilot valve for shifting the main valve at the ends of the strokes. Chenault Patent No. 2,191,369, dated February 20, 1940, shows a rodless pump in which both the main valve and the pilot valve are housed within the motor piston, thereby dispensing with longitudinal passages in the walls of the motor barrel. Such passages not only are dicult and costly to form, but they necessitate thicker walls. Pumps of this type must be installed in tubing of limited cross-sectional dimensions, commonly a two inch inside diameter. Consequently all space occupied by the barrel walls is at the expense of piston area.

The Chenault patent shows a double-acting pump, that is, a pump with inlet and discharge valves at both ends of its barrel. Such a pump must have longitudinal passages in its barrel walls, but was used to balance the load on the motor on its up and down strokes. Singleacting pumps are simpler and have become standard for sucker rod installations. They do not require longitudinal passages in the barrel walls, but ordinarily they deliver iluid only during the stroke in one direction and their power requirements on the two strokes are unbalanced. Nevertheless the greater piston area possible because of the absence of longitudinal wall passages assures that the capacity of a single-acting pump of given outside diameter is at least as great as that of a double-acting pump.

A later Chenault Patent No. 2,679,806, dated lune l, 1954, shows an arrangement for using a motor of the type shown in the iirst Chenault patent with a single-acting pump. Although the power requirements on the two strokes are balanced in this later patent, the volumes of duid delivered to the surface are unequal. The total volume delivered to the surface of course equals the volume of exhaust power fluid displaced by the motor plus the volume which the pump lifts r forces from the well. The motor displaces exhaust power fluid on both strokes, but the pump forces more fluid from the well on its downstroke than on its upstroke. A further disadvantage is that any change in the size of either the motor or pump necessitates a change in the other to maintain balanced power requirements.

An object of the present invention is to provide an improved hydraulic motor and pump combination which altogether avoids longitudinal passages in the barrel walls and has both balanced power requirements and equal fluid deliveries on the two strokes.

atent 0 A further object is to utilize a hydraulic motor resembling that shown in the trst mentioned Chenault patent with a conventional single-acting pump and yet provide balanced power requirements and equal deliveries on both strokes.

A further object is to provide a hydraulic motor and pump combination in which the motor and pump are individually balanced, whereby changes can be made in either without affecting the balance of the other nor of the combination.

A more specific object is to provide a combination of the foregoing type in which the motor has a stationary piston otherwise constructed as shown in the rst mentioned Chenault patent and a traveling barrel, said barrel being coupled to the reciprocable element of a conventional single-acting pump.

In accomplishing these and other objects of the invention, I have provided improved details of structure, a preferred form of which is shown in the accompanying drawings, in which:

Figure l is a diagrammatic vertical sectional View, not to scale, of a motor and pump combination constructed in accordance with my invention;

Figure 2 is a vertical sectional view of the upper portion of the combination more nearly as it actually may be constructed although somewhat simpliied;

Figure 2a is a vertical sectional view of the mid-portion, being a continuation of Figure 2; and

Figure 2b is a vertical sectional View of the lower portion, being a continuation of Figure 2a.

Referring mainly to Figure l, which is much simplied over the actual'construction shown in Figures 2, 2a and 2b, my motor and pump combination is situated at the bottom of a well which contains outer and inner concentric strings of tubing 10 and 12. A stationary upper piston tube 13 is connected to the lower end of the inner tubing 12 through a coupling 14, which contains ports 15 communicating with the outer tubing 1d. A stationary motor piston 16 is ixed to the lower end of the upper piston tube 13 and carries a depending lower piston tube 17, which likewise is stationary. The piston houses a main valve 18 and a pilot valve 19 (Figure 2). The valves and the internal passages in the piston are not disclosed in detail Since they are identical with the showing in Chenault Patent No. 2,191,369. A traveling motor cylinder 20 receives the piston 16 and carries upper and lower cylinder heads 21 and 22 within which the respective piston tubes 13 and 17 are closely fitted. The outer tubing 10 supports a stufling box 23 located below the motor piston and cylinder. The space within the outer tubing bounded by the coupling 1d and stuiiing box 23 forms a chamber C.

A stationary barrel 2d of a standard single-actir1. r pump i is joined at its upper end to the stuiiing box 23. The lower end of this barrel carries a conventional standing valve 25. A pump plunger 26 is mounted for reciprocable movement in the barrel 24 and carries a conventional traveling valve 27. The upper portion of the pump barrel contains relief ports 23 to permit escape of any fluid which leaks past the plunger 26. An extension tube 29 is joined to the bottom of the lower cylinder head 22 of the motor and carries a coupling 3i) at its lower end. A pump tube 31 is joined at its respective ends to the coupling 3) and to the pump plunger 26. The extension tube 29 contains a plurality of ports 32.

To operate the pump, a stream of power oil is pumped from the surface down the inner tubing 12 and upper piston tube 13 into the motor piston 16. The valves within this piston alternately direct this oil to the space within the motor cylinder 26 above the piston and that below the piston. The valves also relieve the other of these spaces to the lower piston tube 17, from which the exhaust Vpower oil Vflows into the chamber C through i the extension tube 29 and its ports 32. Consequently the motor cylinder is driven up and down, and it raises and lowers the pump plunger 26.

For theV motor to be balanced it is only necessary for the upper and lower piston tubes 13 and 17 to beof the same cross-section.l Both the eective power piston area and motorY displacement area on both the upstroke and downstroke are then the same. Numerically Veach of these four quantities equals the cross-sectional area of the bore of the motor cylinder less the cross-sectional area of one of the piston tubes 13 or 17. Therefore on each stroke exhaust power oil displaced from the motor forces oil from the chamber C through the ports 15 and up the Vouter tubing 14B, and the volume of this oil equals that pumped down the wellrto drive the motor.

For the pump to be in balance it is only necessary for the outside cross-sectional area of the pump tube 31 to be one-half the cross-sectional area of the bore of the pump barrel 24. On the downstroke a volume of oil proportional to the cross-sectional area of the bore of the barrel is forced through the traveling valve 27 into the pump tube 51. This tube and also the chamber C already are filled with oil; consequentlya volume of oil equivalent to that forced into the pump Atube 31 is forced from this tube through the extension tube V29 and its ports 32 into the chamber C, blending with the/exhaust power oil from the motor. As the pump tube 31'travels downwardly out of the chamber C, the effective volume of this ychamber Vcontinually increases. With the parts proportioned as described, half the oil forced from the pump tube 31 into the chamber C replaces the volume gained because the pump tube is traveling out of the chamber, and the other half forces oil from this chamber through the ports l5 and up the outer tubing it) to the surface.

On the upstroke the pump tube 31 re-enters the chamber C and the effective volume of this chamber continuously diminishes.Y A corresponding volume of oil again is forced from the chamber through the ports 15 Vand up` the tubing 1b; Because of the proportioning, this volume equals that forced from the chamber on thedownstroke.

rom the foregoing description it is seen that the-motor and pump are individually balanced, and the balance of one is in no way dependent on the balance 'of the other. vConsequently different sizes of either may be substituted without affecting the other.

of that displaced by the Ymotor and that displaced by the pump, tained, the volume from each is the same on both strokes. It `follows, also that the power requirements are the same (neglecting the negligible weight of the moving parts), since the Veffective areas and the volumes deplaced are the same.

f While I have shown and described only a single embodiment of the invention, it is apparent that kmodifications maytarise. to the disclosure set forth but only by the scope of the appended claims. Y Y

l claim: l 1. A hydraulic subsurface motor and pump combina fti'on, the motor portion of said combination comprising a piston of substantially uniform outside diameter, upper and lower stationary'piston tubes of equal cross-sectional area connected to opposite ends of said piston and being of a smaller outside diameter than the piston, a traveling cylinder of substantially Yuniform inside diameter closelyV receiving said piston, upper and lower cylinder heads of equal Cross-sectional area xed to the ends of said cylinder and through which the respectivetubeseex-Y tend in closely received relation, a VmainyalVe and a pilotvalve housed in `said piston for directing 'power iluid from saidruppe'r tube alternately to the uppereend Y VThe volume ofY tluid forced up the well on any stroke equals the sum' As long as proper proportioning is main- Therefore, I do not wishito be limited of said piston, where it acts on the bottom of said upper cylinder head to produce an upstrokeV of said cylinder, and to the lower end of said piston, where it acts on the top of said lower cylinder head to produce a downstroke, said valves relieving the opposite end of said piston in each instance to said lower tube, the pump portion of said combination being singleacting and comprising a stationary cylinder below said traveling cylinder, said stationary cylinder having relief ports adjacent its/upper end, tubing engaging means fixed to said stationarycylinf der above said ports and preventing flow from said ports into the space thereabove, a standing valve `adjacent the lower end ofV said stationary cylinder, a reciprooa'bleelement in said stationary cylinder, a traveling Yvalve in said reciprocable element, a tube connecting said Vreciprocable element with said traveling cylinder, the cross-sectional area of said last named tube being one-half that of the bore of said stationary cylinder,V and means atpthe top of said stationary cylinder closelyreceiving said last named tube and preventing downward flow therepast, whereby the pump delivers substantially Yequal volumes of fluid on both its upstroke and downstroke and the load on the motor is balanced on both strokes.

2. A subsurface pump installation including innerV and outer strings of tubing and a hydraulic motor and pump combination housed within said outer tubing, the motor portion of said combination comprising a piston of substantially uniform outside diameter, upper and vlower stationary piston tubes of equal cross-sectional area connected to opposite ends of said piston and being of a smaller outside diameter than the piston, the upper end of said upper piston tube being connected to the lower end of said inner tubing, a traveling cylinder of substantially uniform inside diameter closely receiving Ysaid, piston, upper and lower cylinder heads Yof equal crosssectional area fixed to the ends of said cylinderV and throughwhich the respective tubes extend in closely received relation, and a main valve and a .pilot valve housed,V

in said piston Vfor directing power lluid from saidcin'ner tubing and said upper tubealternately to the upper end of said piston, where it acts on the bottom of said upf per cylinder head to produce an upstroke of' said cylinder, and to the lower end of said piston, where it 4actsconthe top of said lower cylinder head to produce.a` down.

stroke, said valves relieving the opposite end of :said

piston in each instance to said lower tube, the `pump portion of said combination being single-acting and com- I prising a stationary cylinder below said traveling cylinj der, `said stationary cylinder having relief ports adjacent its upper end, means xed to said stationary cylinder above said ports and engaging said outer tubing to pre` vent 'flow from said ports Vinto the portion of said outer tubing above said stationaryrcylinder,V a standing valve adjacent the lower end of said stationary cylinder, va

reciprocable element in said stationary cylinder, a travel-Vj.`

ing valve in said reciprocable element, a tube connecting said reciprocable element with said traveling cylinder, the cross-sectional area of said last named tube being onehalf that of the bore of said stationary cylinder, and means at the top of said stationary cylinder closely receiving said last named tube and preventing downward flow therepast, whereby the pump delivers substantially equal volumes ,of fluid on both its upstroke and downstroke and the load on the motor is balanced on both Sargent Vlune 5, 1956 

